3.1.3 - pure substance

Question 1

what do pure substances contain?

Answer 1

only ONE type of particles

Question 2

pure substance melting+ boiling point?

Answer 2

have a single sharp melting and boiling point

Question 3

what do mixtures contain?

Answer 3

different types of particle

Question 4

mixtures melting + boiling point?

Answer 4

melt and boil over a range of temperatures

Question 5

what is an element?

Answer 5

a substance containing only one kind of atom

Question 6

what is a compound?

Answer 6

a substance containing different types of atoms which are chemically bonded together

Question 7

chemical test for water?

Answer 7

anhydrous copper(II) sulphate
turns white -> blue

Question 8

physical tests for water?

Answer 8

melting point = 0 degrees
boiling point = 100 degrees
pure water would melt/boil exactly on this temp

Question 9

properties of metals:

Answer 9

• high MP/BP
• electrical conductors
• malleable
• shiny
• form alkaline oxides

Question 10

properties of non-metals:

Answer 10

• low MP/BP
• electrical insulators
• brittle
• dull
• form acidic oxides

Question 11

what is element combustion?

Answer 11

when an element reacts with oxygen to produce an oxide

Question 12

element combustion equation?

Answer 12

element + oxygen -> element oxide

Question 13

combustion of magnesium equation?

Answer 13

magnesium + oxygen -> magnesium oxide

2Mg + O2 -> 2MgO

Question 14

observations of combustion of magnesium?

Answer 14

bright white light
white powder formed

Question 15

combustion of sulphur equation?

Answer 15

sulphur + oxygen -> sulphur dioxide

S + O2 -> SO2

Question 16

observations of combustion of sulphur?

Answer 16

blue flame

Question 17

combustion of hydrogen equation?

Answer 17

hydrogen + oxygen -> water

2H2 + O2 -> 2H2O

Question 18

observations of combustion of hydrogen?

Answer 18

squeaky pop

Question 19

when metal oxides dissolve in water do they form an acidic or alkaline solution?

Answer 19

alkaline

Question 20

when non-metal dioxides dissolve in water do they form an acidic or alkaline solution?

Answer 20

acidic

Question 21

what bonding happens between metals?

Answer 21

metallic bonding

Question 22

what bonding happens between non-metals?

Answer 22

covalent bonding

Question 23

what bonding happens between metals and non-metals?

Answer 23

ionic bonding

Question 24

what does the name and state of the oxide formed in element combustion depend on

Answer 24

whether the element was a metal or non-metal

metal -> metal oxide (solid)
non-metal -> non-metal oxide (gas)

Question 25

what can you do to determine whether an unknown element is metal or non-metal

Answer 25

- combust it in oxygen - dissolve the oxide formed - check the pH of the solution with an indicator

Question 26

what is a compound

Answer 26

a substance containing more than one type of atom, chemically bonded together

Question 27

how can compounds often be formed

Answer 27

heating their elements together eg. if you heat zinc and sulphur you make zinc sulphide

Question 28

what are the three types of compounds

Answer 28

metallic ionic covalent

Question 29

which compound bonds non-metals

Answer 29

covalent

Question 30

which compound bonds metals and non-metals

Answer 30

ionic

Question 31

which compound bonds metals

Answer 31

metallic